Total Productive Maintenance (TPM), unlike many other maintenance method- ologies, directly links maintenance to business performance and practices. Ac- cording to Hutchins (1998), TPM challenges the view that maintenance is
done in the background and only appears when it is needed – meaning when something is broken.
History and Formation of TPM
The concept of TPM comes from Japan, according to Venkatesh (2007) the origins of TPM can be traced back to 1951. At the time, preventive mainte- nance was introduced to Japan after the Second World War from the United States. Nippondenso, a large automobile supplier, was one of the first Japanese companies to introduce complete PM in 1960. The PM used entailed operators producing goods and the maintenance group dedicated to the maintaining of machines. This, however, very soon became a problem within Nippondenso, due to their high level of automation. Management then decided to make routine maintenance the responsibility of the operator, this became known as autonomous maintenance, a predominant feature of TPM.
This decision caused Nippondenso to have an active preventive mainte- nance program and an added autonomous programme performed by operators. The maintenance crew then only performed essential maintenance work, the total company wide maintenance program then consisted of revertive main- tenance, together with maintenance prevention and maintainability improve- ment. This gave rise to Total Productive Maintenance.
The TPM Framework
Ever increasing global competitiveness has, according to Brah and Chong (2004), raised the importance of TPM in gaining and sustaining a compet- itive advantage. Organisations are seeking proactive tools such as TPM, in order to boost their competitive position. TPM, as detailed by Brah and Chong (2004), covers the entire life of equipment in every division of the or- ganisation including planning, manufacturing and maintenance. It creates a relationship between all organisational functions but particularly between production and maintenance that have traditionally stood apart. The Japan Institute of Plant Maintenance (1990) argues that both operations and main- tenance departments should accept the responsibility of keeping equipment in a good condition. Nakajima (1988) states that this relationship between production and maintenance departments drives continuous improvement of product quality, operational efficiency, capacity assurance and safety.
Nakajima (1988) also puts forward a definition of the word “total” that forms part of the name TPM, he states that it has three meanings:
1. Total effectiveness: pursuit of economic efficiency and profitability. 2. Total maintenance system: includes maintenance prevention, mainte-
nance improvement and PM.
3. Total participation: refers to the fact that all employees, including oper- ators, are expected to take responsibility for maintenance activities and that maintenance is a team effort.
Nakajima (1988), being the founder of TPM as we know it, also provides us with the five pillars of TPM, these are:
1. Maximise overall equipment effectiveness.
2. Establish a thorough system of preventive maintenance for the equip- ment’s entire life span.
3. Implement TPM by involving all departments.
4. Involve every single employee, from top management to line worker. 5. Promote TPM through so called motivation management; autonomous
small groups.
As one can see from the above mentioned five pillars, the TPM method- ology is very much tuned to a heavy manufacturing environment, as it orig- inated from this industry. McKone et al. (1999) state that TPM provides a comprehensive company-wide approach to maintenance management that in- volves all employees of the organisation, it is usually split into a short-term and long-term element. The short-term focuses on the autonomous maintenance programme within the production department and a planned maintenance pro- gramme within the maintenance department. In the long-term view, the focus is on new equipment design and a concerted effort to get rid of lost equip- ment time. In his book, Hartmann (1992) describes many differences between TPM as used in Japan and how it is used in the United States. The author states that it is very important to customise the TPM process to work for a specific environment and the cultures of different people. He suggests that there are unique external and specific factors, such as country, plant and man- agement aspects, to any TPM implementation. Both Powell (1995) and Brah
et al. (2002) suggest that top management support and planning leads to the
Autonomous Maintenance
Both Suzuki (1992) and Nakajima (1988) state that autonomous maintenance is one of the most important steps within the short-term effort. At the core of Autonomous maintenance is the 5 S’s strategy: seiri, sexton, seiso, seiketsu and shitsuke. These are Japanese words and can be translated as: organisa- tion, tidiness, purity, cleanliness and discipline. The 5 S’s concept is essentially a housekeeping notion. Hutchins (1998) compares the cleaning activities to steam cleaning the engine of a car. When the car is dirty, it is impossible to tell if any screws are missing or if there are any fluid leaks. However, when clean, missing screws and leaking fluid can easily be identified. The added benefit to this procedure, according to Hutchins (1998), Suzuki (1992) and Nakajima (1988), is that the operator will begin to gain a better understand- ing of the machine and how it works. Brah and Chong (2004) state that TPM depends on operators to perform autonomous routine maintenance and, con- tinuous improvement being a fundamental element of a TPM program, this again depends on the worker’s willingness to accept changes and adapt to new environments.
Overall Equipment Effectiveness
Overall Equipment Effectiveness (OEE) is one of the main goals and measures of TPM. The OEE ratio is defined by both Willmott and McCarthy (2001) and Hutchins (1998) in equation 2.5.
OEE = availability × performance × quality rate (2.5)
where,
availability = proportion of the total time during which the equipment is available.
performance = measures of how close the average cycle time is to the theoretical minimum.
quality rate = proportion of the processed quantity that is of acceptable quality.
According to Hutchins (1998), typical OEE calculations range between 40% and 50% before implementation, and can rise up to between 80% and 90%. Nakajima (1988) states that the basis for OEE comes from the fact that the objective of any production improvement activity is to increase productivity by minimising input and maximising output. By output the author also includes quality, reducing costs and meeting delivery dates, while increasing worker morale and improving health and safety.
Nakajima (1988) defines input as labour, machine and materials. Output is defined as production (P), quality (Q), cost (C), delivery (D), safety, health and environment (S) and morale (M). In the end, TPM attempts to maximise the PQCDSM output, this is achieved by creating and maintaning optimal operating conditions and running machines effectively. In order to achieve OEE, the TPM methodology defines “six big losses” that TPM works to reduce and eliminate. These losses are defined by TPMs founder, Nakajima (1988) as:
Downtime:
1. Equipment failure (breakdowns) 2. Setup/adjustment
Speed losses:
3. Idling and minor stoppages 4. Reduced speed
Defect:
5. Process defects 6. Reduced yield
Hutchins (1998) states that cost effectiveness is a result of an organisation’s ability to eliminate the causes of the above mentioned losses that reduce the OEE. Chan et al. (2005) state that OEE is an effective way of analysing the efficiency of a single machine, as well as a complete and integrated manufactur- ing system. Willmott and McCarthy (2001), however, state that OEE cannot only be used to assess machinery, but should be applied to the entire business, monitoring the effectiveness of the whole value chain. OEE is a direct help to the operator and the core TPM team, to focus their efforts in limiting and eliminating the six losses stated above.